Development of a stable faceted tungsten emitter surface
High work function stable faceted W thermionic emitter surface preparation by electroetching and vapor deposition
Danko, J. C.↗
SEARCH · Search NASA
Results for “stable”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
A rugged, stable, differential platinum resistance thermometer
Rugged stable differential Pt resistance thermometer for Lunar Heat Flow Program, discussing construction, calibration and environmental test
Felsenthal, P.↗
Nonlinear absolutely stable regulator design in parameter space
Nonlinear absolutely stable regulator design in parameter space, using computer simplex search
Karmakar, J. S.↗
Ogo 5 measurements of the plasmasphere during observations of stable auroral red arcs
Hydrogen ion concentration measurements by OGO 5 in plasmasphere during intense magnetic storms accompanied by stable auroral red arcs
Chappell, C. R.↗
Stable limit cycles and triggering limits of the first radial model in unstable liquid rockets
Stable limit cycles and triggering limits of first radial mode in nonlinearly unstable liquid propellant rocket motors, using wave equation and Galerkin method
Powell, E. A.↗
Thermally stable polyimides from solutions of monomeric reactions
Thermally stable polyimide graphite fiber reinforced composites from solutions of monomeric reactions, comparing amide acid prepolymers
Delvigs, P.↗
Mechanically and thermally stable maser cavity resonator
New type cavity resonator is designed for hydrogen maser. Resonator consists of three pieces of glass-ceramic material having extremely low thermal coefficient of expansion and provides very stable mechanical tuning.
Vessot, R. F. C.↗
Ultraviolet and thermally stable polymer compositions
Copolymers, produced from aromatic substituted aromatic azine-siloxane compositions, are thermally stable, solar ultraviolet light non-degradable by wavelengths shorter than those reaching earth surface.
Adamson, M. J.↗
Thermally stable polyimides from solutions of monomeric reactants
A method for preparing thermally stable resin-fiber-reinforced composites by using solutions of appropriate monomers is described. Solutions containing a dimethyl ester of an aryl tetracarboxylic acid, the monomethyl ester of nadic acid, and an aryl diamine were used to impregnate graphite fibers. Composites fabricated from these prepregs exhibited excellent thermo-oxidative stability and retention of mechanical properties at 315 C (600 F). These results compare favorably to those obtained from composites made from amide-acid prepolymers capped with reactive alicyclic rings. Monomeric solutions provide excellent shelf life and improved solubility compared to amide-acid prepolymer solutions.
Serafini, T. T.↗
Thermally stable laminating resins
Improved thermally stable laminating resins were developed based on the addition-type pyrolytic polymerization. Detailed monomer and polymer synthesis and characterization studies identified formulations which facilitate press molding processing and autoclave fabrication of glass and graphite fiber reinforced composites. A specific resin formulation, termed P10P was utilized to prepare a Courtaulds HMS reinforced simulated airfoil demonstration part by an autoclave molding process.
Jones, R. J.↗
Development of space stable thermal control coatings for use on large space vehicles
The evaluation and environmental testing of zinc orthotitanate pigments for use as space stable thermal control coatings on large space vehicles are discussed. Electron paramagnetic resonance spectra of the pigments and their precursor compounds are examined. A continuing study of the spectral intensity of mercury-argon and mercury-xenon sources in reported. Results of long term environmental testing of commercially available, strippable, protective coatings are discussed.
Gilligan, J. E.↗
Calculated and observed features of stable auroral red arcs during three geomagnetic storms.
Satellite electron temperature and density data are used to calculate the structure of several stable auroral red arcs (SAR arcs) according to the thermal conduction model of the arc. The calculated lambda 6300 emission rates are compared with ground-based photometric observations taken at the same time and in the vicinity of the satellite crossings of the arcs. The SAR arcs analyzed include a range of lambda 6300 intensities, geographical locations, and times during the associated geomagnetic storm. In addition, satellite data were obtained at different altitudes over and within the SAR-arc region. Enhanced electron temperatures within or on the equatorward edge of an electron-density depression are common features of all the SAR arcs examined. There is general agreement between the calculated and observed lambda 6300 emission features for SAR arcs observed during the geomagnetic storm periods of Oct. 29 to Nov. 2, 1968, May 14-15, 1969, and Mar. 8-9, 1970. For these SAR arcs, thermal conduction from the magnetosphere alone is sufficient to excite the lambda 6300 emission to its observed intensity.
Roble, R. G.↗
A new intermediate for the production of flexible stable polymers
Method of incorporating ether linkages into perfluoroalkylene segment of a dianydride intermediate yields intermediate that may be used in synthesis of flexible, stable polyimides for use as high-temperature, solvent-resistant sealants.
Webster, J. A.↗
Finite element solution for energy conservation using a highly stable explicit integration algorithm
Theoretical derivation of a finite element solution algorithm for the transient energy conservation equation in multidimensional, stationary multi-media continua with irregular solution domain closure is considered. The complete finite element matrix forms for arbitrarily irregular discretizations are established, using natural coordinate function representations. The algorithm is embodied into a user-oriented computer program (COMOC) which obtains transient temperature distributions at the node points of the finite element discretization using a highly stable explicit integration procedure with automatic error control features. The finite element algorithm is shown to posses convergence with discretization for a transient sample problem. The condensed form for the specific heat element matrix is shown to be preferable to the consistent form. Computed results for diverse problems illustrate the versatility of COMOC, and easily prepared output subroutines are shown to allow quick engineering assessment of solution behavior.
Baker, A. J.↗
Development of space stable thermal control coatings for use on large space vehicles
A reserach project to develop space stable thermal control coatings for large surfaces is discussed. Four major tasks are considered: (1) pigment development, (2) binder development, (3) environmental effects evaluations, and (4) general coatings investigations.
Gilligan, J. E.↗
Vertical distribution of vibrational energy of molecular nitrogen in a stable auroral red arc and its effect on ionospheric electron densities
Previous solutions of the problem of the distribution of vibrationally excited molecular nitrogen in the thermosphere have either assumed a Boltzmann distribution and considered diffusion as one of the loss processes or solved for the energy level populations and neglected diffusion. Both of the previous approaches are combined by solving the time dependent continuity equations, including the diffusion process, for the first six energy levels of molecular nitrogen for conditions in the thermosphere corresponding to a stable auroral red arc. The primary source of molecular nitrogen excitation was subexcitation, and inelastic collisions between thermal electrons and molecular nitrogen. The reaction rates for this process were calculated from published cross section calculations. The loss processes for vibrational energy were electron and atomic oxygen quenching and vibrational energy exchange. The coupled sets of nonlinear, partial differential equations were solved numerically by employing finite difference equations.
Newton, G. P.↗
Throat-bypass bleed systems for increasing the stable airflow range of a Mach 2.50 axisymmetric inlet with 40-percent internal contraction
The results of an experimental investigation to increase the stable airflow range of a super sonic mixed-compression inlet are presented. Various throat-bypass bleeds were located on the inlet cowl. The bleed types were distributed porous normal holes, a forward slanted slot, or distributed educated slots. Large inlet stability margins were obtained with the inlet throat bleed systems if a constant pressure was maintained in the throat-bypass bleed plenum. Stability limits were determined for steady-state and limited transient internal air flow changes. Limited unstart angle-of-attack data are presented.
Sanders, B. W.↗
Method and apparatus for stable silicon dioxide layers on silicon grown in silicon nitride ambient
A method and apparatus for thermally growing stable silicon dioxide layers on silicon is disclosed. A previously etched and baked silicon nitride tube placed in a furnace is used to grow the silicon dioxide. First, pure oxygen is allowed to flow through the tube to initially coat the inside surface of the tube with a thin layer of silicon dioxide. After the tube is coated with the thin layer of silicon dioxide, the silicon is oxidized thermally in a normal fashion. If the tube becomes contaminated, the silicon dioxide is etched off thereby exposing clean silicon nitride and then the inside of the tube is recoated with silicon dioxide. As is disclosed, the silicon nitride tube can also be used as the ambient for the pyrolytic decomposition of silane and ammonia to form thin layers of clean silicon nitride.
Cohen, R. A.↗